1. Field of the Invention
Example embodiments generally relate to a fixing device and an image forming apparatus, and more particularly, to a fixing device for fixing a toner image on a recording medium and an image forming apparatus including the fixing device.
2. Description of the Related Art
Related-art image forming apparatuses, such as copiers, facsimile machines, printers, or multifunction printers having at least one of copying, printing, scanning, and facsimile functions, typically form an image on a recording medium according to image data. Thus, for example, a charger uniformly charges the surface of an image carrier; an optical writer emits a light beam onto the charged surface of the image carrier to form an electrostatic latent image on the image carrier according to the image data; a development device supplies toner to the electrostatic latent image formed on the image carrier to make the electrostatic latent image visible as a toner image; the toner image is directly transferred from the image carrier onto a recording medium or is indirectly transferred from the image carrier onto a recording medium via an intermediate transfer member; a cleaner then collects residual toner not transferred and remaining on the surface of the image carrier after the toner image is transferred from the image carrier onto the recording medium; finally, a fixing device applies heat and pressure to the recording medium bearing the toner image to fix the toner image on the recording medium, thus forming the image on the recording medium.
Such fixing device may include a fixing roller and a pressing roller pressing against each other to form a nip therebetween. As a recording medium bearing a toner image passes through the nip, the fixing roller applies heat to the recording medium to melt the toner image and fix it on the recording medium. However, it can happen that the melted toner, which contains resin to facilitate melting, may move to the fixing roller contacting the toner image on the recording medium during fixing. Consequently, the melted toner adhered to the fixing roller may wind the recording medium around the fixing roller. Moreover, when a toner image is formed on both sides of the recording medium by duplex printing, the heated toner on the back side of the recording medium contacting the pressing roller also may wind the recording medium around the pressing roller.
To address this problem, a pawl-shaped or plate-shaped separation member may be disposed opposite the fixing roller or the pressing roller to separate the recording medium from the fixing roller or the pressing roller.
In addition, a slight gap of predetermined size is generally retained between a front edge portion of the separation member and the surface of the fixing roller or the pressing roller to improve the ability of the separation member to separate the recording medium from the fixing roller or the pressing roller.
Further, the front edge portion of the separation member is disposed closer to the nip to improve the performance of the separation member. For example, when relatively thin paper is used as a recording medium, the front edge portion of the separation member needs to be closer to the nip than when relatively thick paper is used. However, the front edge portion of the separation member disposed closer to the nip may scratch the toner image on the recording medium passing through the nip, resulting in formation of the streaked toner image. Alternatively, the toner on the recording medium may adhere to the front edge portion of the separation member and then adhere to the recording medium again, staining the recording medium. Moreover, when the recording medium is jammed between the fixing roller and the pressing roller, the front edge portion of the separation member disposed closer to the nip may hinder manual removal of the recording medium.